package com.badlogic.gdx.graphics.g3d.particles.influencers;

import com.badlogic.gdx.graphics.g3d.particles.ParallelArray.FloatChannel;
import com.badlogic.gdx.graphics.g3d.particles.ParticleChannels;
import com.badlogic.gdx.graphics.g3d.particles.values.GradientColorValue;
import com.badlogic.gdx.graphics.g3d.particles.values.ScaledNumericValue;
import com.badlogic.gdx.math.MathUtils;
import com.badlogic.gdx.utils.Json;
import com.badlogic.gdx.utils.JsonValue;

/** It's an {@link Influencer} which controls particles color and transparency. 
 * @author Inferno */
public abstract class ColorInfluencer extends Influencer{
	
	/** It's an {@link Influencer} which assigns a random color when a particle is activated. */
	public static class Random extends ColorInfluencer{
		FloatChannel colorChannel;
		
		@Override
		public void allocateChannels() {
			colorChannel = controller.particles.addChannel(ParticleChannels.Color);
		}
		
		@Override
		public void activateParticles (int startIndex, int count) {
			for(int 	i=startIndex*colorChannel.strideSize,  c = i +count*colorChannel.strideSize; 
				i < c; 
				i +=colorChannel.strideSize){
				colorChannel.data[i+ParticleChannels.RedOffset] = MathUtils.random();
				colorChannel.data[i+ParticleChannels.GreenOffset] = MathUtils.random();
				colorChannel.data[i+ParticleChannels.BlueOffset] = MathUtils.random();
				colorChannel.data[i+ParticleChannels.AlphaOffset] = MathUtils.random();
			}
		}

		@Override
		public Random copy () {
			return new Random();
		}
	}
	
	/** It's an {@link Influencer} which manages the particle color during its life time. */
	public static class Single extends ColorInfluencer {
		FloatChannel alphaInterpolationChannel;
		FloatChannel lifeChannel;
		public ScaledNumericValue alphaValue;
		public GradientColorValue colorValue;
		
		public Single(){
			colorValue = new GradientColorValue();
			alphaValue = new ScaledNumericValue();
			alphaValue.setHigh(1);
		}

		public Single (Single billboardColorInfluencer) {
			this();
			set(billboardColorInfluencer);
		}

		public void set(Single colorInfluencer){
			this.colorValue.load(colorInfluencer.colorValue);
			this.alphaValue.load(colorInfluencer.alphaValue);
		}
		
		@Override
		public void allocateChannels () {
			super.allocateChannels();
			//Hack this allows to share the channel descriptor structure but using a different id temporary
			ParticleChannels.Interpolation.id = controller.particleChannels.newId();
			alphaInterpolationChannel = controller.particles.addChannel(ParticleChannels.Interpolation);
			lifeChannel = controller.particles.addChannel(ParticleChannels.Life);
		}
		
		@Override
		public void activateParticles (int startIndex, int count) {
			for(int 	i=startIndex*colorChannel.strideSize, 
							a = startIndex*alphaInterpolationChannel.strideSize,
							l = startIndex*lifeChannel.strideSize + ParticleChannels.LifePercentOffset,
							c = i +count*colorChannel.strideSize; 
							i < c; 
							i +=colorChannel.strideSize, 
							a +=alphaInterpolationChannel.strideSize,
							l +=lifeChannel.strideSize){
				float alphaStart = alphaValue.newLowValue();
				float alphaDiff = alphaValue.newHighValue() - alphaStart;
				colorValue.getColor(0, colorChannel.data, i);
				colorChannel.data[i+ParticleChannels.AlphaOffset] = alphaStart + alphaDiff*alphaValue.getScale(lifeChannel.data[l]);
				alphaInterpolationChannel.data[a+ParticleChannels.InterpolationStartOffset] = alphaStart;
				alphaInterpolationChannel.data[a+ParticleChannels.InterpolationDiffOffset] = alphaDiff;
			}
		}

		@Override
		public void update () {
			for(int 	i=0, a = 0, l = ParticleChannels.LifePercentOffset,
				c = i +controller.particles.size*colorChannel.strideSize; 
				i < c; 
				i +=colorChannel.strideSize, a +=alphaInterpolationChannel.strideSize, l +=lifeChannel.strideSize){
				
				float lifePercent = lifeChannel.data[l];
				colorValue.getColor(lifePercent, colorChannel.data, i);
				colorChannel.data[i+ParticleChannels.AlphaOffset] = alphaInterpolationChannel.data[a+ParticleChannels.InterpolationStartOffset] 
					+ alphaInterpolationChannel.data[a+ParticleChannels.InterpolationDiffOffset] *alphaValue.getScale(lifePercent);
			}
		}
		
		@Override
		public Single copy () {
			return new  Single(this);
		}
		
		@Override
		public void write (Json json) {
			json.writeValue("alpha", alphaValue);
			json.writeValue("color", colorValue);
		}
		
		@Override
		public void read (Json json, JsonValue jsonData) {
			alphaValue = json.readValue("alpha", ScaledNumericValue.class, jsonData);
			colorValue = json.readValue("color", GradientColorValue.class, jsonData);
		}
	}
	
	FloatChannel colorChannel;
	
	@Override
	public void allocateChannels() {
		colorChannel = controller.particles.addChannel(ParticleChannels.Color);
	}	
}
